Digital video broadcasting (DVB) signals include the video and audio components of broadcast content, as well as other information. For example, a receiver of a digital transmission needs control data for its technical function, such as so-called “Packet_Identifiers” (PID) among others, so that when the Packaged Elementary Streams (PES) are demultiplexed from the received transportation stream, the compressed video or audio data contained therein can be functionally assigned. These control data are transmitted as “sections” in the so-called Program Specific Information (PSI), which may be expanded in accordance with the service provider's needs by means of additional sections, so-called “Private-Sections”.
This expansion is used in the DVB system. In that way the DVB signals also transmit Service Information (SI) in addition to the program specific information (PSI). Throughout the specification, the term SI encompasses any kind of information additional to the video and audio content, such as but not limited to, the service information and PSI. The service information (SI) contains technical transmission data and particularly describes the Program Elementary Streams (PES) according to origin and content. This makes it possible to automatically tune the receiver for the desired service and provides a user-friendly guide through the variety of the transmitted services by means of an electronic program guide (EPG).
In accordance with certain standards, for example, the PSI data and SI data are transmitted in the same form. Thus a transport multiplexer serially transmits data packets with elementary video streams, elementary audio streams and data streams with PSI or SI data, in a sequence with variable limits.
For example, in accordance with certain standards, both the PSI and the SI data may be arranged in the form of tables and subtables of different lengths. The SI tables use the syntax of the PSI standards and contain so-called “descriptors” to describe the contents and the transmission data. The contents of the SI tables can differ depending on the service provider. A significant component is the included information about services and their contribution to the programs, so-called “events” of the received distributor network and from other distributor networks. For example, by means of so-called SDT “Service Description Tables” they contain data for a more detailed description of the individual services, such as among other things the name of the service and the provider, the type of service and its national or regional availability.
TV viewers do not generally concern themselves with SI, and merely enjoy the video and audio content of the broadcast.